Industry has utilized compounds based on fluorocarbon chemistry for many years to produce articles having improved resistance to penetration by oil and grease, due to the ability of fluorocarbons to lower the surface energy of the articles. One emerging issue with the use of perfluorinated hydrocarbons is that they are remarkably persistent in the environment. The EPA and FDA have recently begun a review of the source, environmental fate, and toxicity of these compounds. A recent study reported a very high (>90%) rate of occurrence of perfluorooctane sulfonate in blood samples taken from school children. The expense and potential environmental liability of these compounds has driven manufacturers to seek alternative means of producing articles having resistance to penetration by oil and grease.
While lowering the surface energy improves the penetration resistance of the articles, lowering the surface energy also has some disadvantages. For example, a textile fabric treated with a fluorocarbon will exhibit good stain resistance; however, once soiled, the ability of cleaning compositions to penetrate and hence release the soil from the fabric, which may result in permanently soiled fabrics of reduced useful life. Another example is a greaseproof paper which is to be subsequently printed and or coated with an adhesive. In this case the requisite grease resistance is attained by treatment with the fluorocarbon, but the low surface energy of the paper may cause problems related to printing ink or adhesive receptivity, including blocking, back trap mottle, poor adhesion, and register. If a greaseproof paper is to be used as a release paper having an adhesive applied, the low surface energy may reduce the strength of the adhesion. To improve their printability, coatability or adhesion, the low surface energy articles can be treated by a post forming processes such as corona discharge, chemical treatment, flame treatment, or the like. However, these processes increase the cost of producing the articles and may have other disadvantages.
Prolamines are proteinaceous compounds present as the storage proteins of cereal grains. For example, zein is a prolamine found in corn gluten meal, a by-product of corn milling. Since the primary use for corn gluten meal is animal feed, which typically sells for a low price, there has been a great deal of interest in the development of value added products from zein. Unfortunately, the suitable applications for zein have been limited due to its lack of solubility in water.